title: Influence of lithium on mammary tumor growth in vivo.
abstract: The possibility that lithium ions stimulate growth of mammary tumors in vivo has been suggested by their mitogenic action in vitro on normal and neoplastic mammary epithelium [8] and their clinical use as stimulators of neutrophil production in tumor-bearing patients treated with cytotoxic drugs [14,15]. Three experiments were performed to assess this possibility. Buffalo/N female rats received a single injection of N-nitrosomethylurea (NMU) at a dose known to produce mammary carcinomas in about 50% of animals under standard conditions. Under lithium treatment, the incidence of tumors did not increase significantly. Sprague-Dawley female rats treated with a single dose of 7,12-dimethylbenz[alpha] anthracene (DMBA), but showing no mammary tumors after 4 months, received lithium in their drinking water for 3 additional months. The number of late-appearing tumors was not increased by lithium treatment. Buffalo/N females with NMU-induced tumors were castrated, and the subsequent changes in tumor volume were compared in lithium-treated and control animals. The regression-regrowth curves were not altered by lithium treatment. These results are in contrast to the growth stimulatory capacity of lithium on mammary epithelium observed in vitro [8] and indicate it is very unlikely that lithium ions have an undesirable growth stimulatory action on primary mammary carcinomas in vivo.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D005260:Female; D008094:Lithium / Q000633:toxicity*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced*; D008770:Methylnitrosourea; D009368:Neoplasm Transplantation; D051381:Rats
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D008770:Methylnitrosourea; D008094:Lithium